ESLint is an open-source tool used in web development to analyze, validate, and enforce coding styles and conventions for JavaScript code, and to detect and report potential errors, vulnerabilities, or inconsistencies. ESLint is used in various web technologies, such as React, Vue.js, or Node.js, and can provide powerful features, such as custom rules, auto-fixing, or integration with code editors, that can improve the quality, readability, and maintainability of web applications. ESLint can also facilitate the collaboration, portability, and scalability of web projects, and can reduce the risk of introducing bugs or security issues.